The oil and gas industry expends sizable sums to design cutting tools, such as downhole drill bits including roller cone bits, also termed “rock” bits as well as fixed cutter bits, which have relatively long service lives, with relatively infrequent failure. In particular, considerable sums are expended to design and manufacture roller cone rock bits and fixed cutter bits in a manner that minimizes the opportunity for catastrophic drill bit failure during drilling operations. The loss of a roller cone or a polycrystalline diamond compact (PDC) from a fixed cutter bit during drilling operations can impede the drilling operations and, at worst, necessitate rather expensive fishing operations. If the fishing operations fail, sidetrack-drilling operations must be performed in order to drill around the portion of the wellbore that includes the lost roller cones or PDC cutters. Typically, during drilling operations, bits are pulled and replaced with new bits even though significant service could be obtained from the replaced bit. These premature replacements of downhole drill bits are expensive, since each trip out of the well prolongs the overall drilling activity by wasting valuable rig time and consumes considerable manpower, but are nevertheless done in order to avoid the far more disruptive and expensive process of, at best, pulling the drillstring and replacing the bit or fishing and side track drilling operations necessary if one or more cones or compacts are lost due to bit failure.
With the ever-increasing need for downhole drilling system dynamic data, a number of “subs” (i.e., a sub-assembly incorporated into the drillstring above the drill bit and used to collect data relating to drilling parameters) have been designed and installed in drillstrings. Unfortunately, these subs cannot provide actual data for what is happening operationally at the bit due to their physical placement above the bit itself.
Data acquisition is conventionally accomplished by mounting a sub in the Bottom Hole Assembly (BHA), which may be several feet to tens of feet away from the bit. Data gathered from a sub this far away from the bit may not accurately reflect what is happening directly at the bit while drilling occurs. Often, this lack of data leads to conjecture as to what may have caused a bit to fail or why a bit performed so well, with no directly relevant facts or data to correlate to the performance of the bit.
Recently, data acquisition systems have been proposed to be installed in the drill bit itself. However, data gathering, storing, and reporting from these systems have been limited. In addition, conventional data gathering in drill bits has not had the capability to adapt to drilling events that may be of interest in a manner allowing more detailed data gathering and analysis when these events occur.
There is a need for a drill bit equipped to gather, store, and analyze long-term data that are related to cutting performance and condition of the drill bit. A drill bit so equipped may; extend useful bit life enabling re-use of a bit in multiple drilling operations, determine when a drill bit is near its end of life and should be changed, and develop drill bit performance data on existing drill bits, which also may be used for developing future improvements to drill bits.